There is a known recording device which is used, connected a television set, for example, when a plurality of television programs are recorded simultaneously or when a long program is recorded. This type of recording device comprises a box-type housing. A plurality of storage devices and a circuit board which controls the storage devices are contained in the housing. The circuit board comprises, for example, a plurality of circuit components such as a semiconductor package and chip components. Particular circuit components which consume much electric power inevitably increase the heat produced. Therefore, conventionally, such cool particular circuit components are subjected to forced cooling by using a fan.
For example, according to the electronic apparatus disclosed in Jpn. Pat. Appin. KOKAI Publication No. 2001-57493, a fan is provided on a printed circuit board where circuit components which produce heat are mounted. The fan comprises a casing and an impeller. The casing has a flat box-type shape and comprises a bottom plate, a top plate, and side plates. The casing comprises a bearing tube which protrudes from the bottom plate to the top plate. The impeller, together with a motor, is supported by the bearing tube and is contained inside the casing.
The bottom plate and top plate of the housing each are provided with air intake holes which draw air from inside the housing. The air intake holes in the bottom plate are open to an air intake space formed between the bottom plate and the printed circuit board, and are positioned immediately above a circuit component which produces heat. The air intake hole in the top plate is open in a space at an upper part in the housing. As the impeller rotates, air in the housing is drawn into the casing from the air intake holes in the top and bottom plates. The drawn air is discharged to outside of the housing from an exhaust port formed in a side plate of the casing.
In the electronic apparatus disclosed in the foregoing publication, heat from the circuit component is discharged into the air intake space between the bottom plate of the casing and the printed circuit board. Therefore, a temperature of the air intake space increases. Since the air intake holes formed in the bottom plate of the casing are open to the air intake space, heated air discharged from the circuit component into the air intake space is further drawn along an air flow into air intake holes of the fan. As a result, no heat from the circuit component stays in a space between the printed circuit board and the fan.
In the electronic apparatus disclosed in the foregoing publication, an entire open area covering the air intake holes formed in the bottom plate of the casing faces the printed circuit board. According to such a configuration, the air intake holes in the bottom plate can draw air only from the air intake space positioned between the bottom plate and the printed circuit board. The air intake space tends to be narrower and narrower as thinning of the housing. Therefore, the fan cannot avoid great resistance from occurring when air is drawn from the air intake space.
As a result, regardless of that the fan draws air in two directions from the bottom and top plates of the casing, heat from the circuit component which tends to stay in the space between the bottom plate and the printed circuit board of the casing. Such heat from the circuit component is difficult to take in efficiently. Accordingly, a temperature in the periphery of the circuit component increases and hinders thermal radiation performance of the circuit component.